diff --git a/src/main/java/net/imagej/ops/image/cooccurrenceMatrix/CooccurrenceMatrix3D.java b/src/main/java/net/imagej/ops/image/cooccurrenceMatrix/CooccurrenceMatrix3D.java
index 66e65e4690..a26e6fe3c5 100644
--- a/src/main/java/net/imagej/ops/image/cooccurrenceMatrix/CooccurrenceMatrix3D.java
+++ b/src/main/java/net/imagej/ops/image/cooccurrenceMatrix/CooccurrenceMatrix3D.java
@@ -126,7 +126,8 @@ public double[][] calculate(final IterableInterval<T> input) {
 							&& pixels[sz][sy][sx] != Integer.MAX_VALUE) {
 
 						matrix[pixels[z][y][x]][pixels[sz][sy][sx]]++;
-						nrPairs++;
+						matrix[pixels[sz][sy][sx]][pixels[z][y][x]]++;
+						nrPairs += 2;
 
 					}
 				}